Alginate-supported L-arginine as biobased heterogeneous catalyst for the conversion of glycidol and CO 2 into glycerol carbonate

Abstract

Glycerol carbonate is emerging as a safe and sustainable CO2-based chemical with multiple attractive applications. Among various synthetic strategies, the preparation of glycerol carbonate from CO2 and glycidol, a glycerol derivative, is an atomeconomic, thermodynamically favourable process that does not require the use of sacrificial reagents. In this work, we report the rational design, synthesis and application of a novel biobased catalyst for this reaction, which was prepared by grafting of L-arginine onto a sodium alginate support. This synthetic approach resulted in a heterogeneous, metal-and halide-free catalyst with the desirable combination of active sites (basic, nucleophilic sites and hydrogen bond donors) for glycidol activation, leading to much higher glycerol carbonate yield and selectivity compared to previously reported biobased heterogeneous catalysts for this reaction. The catalyst can operate under mild conditions (45-80 °C, 10-30 bar CO2) and showed good recyclability. Careful physicochemical characterization by FTIR, NMR, XPS, TGA, elemental analysis and GPC allowed to define structure-activity relationships and to identify the suitable reaction conditions to prevent undesirable catalyst degradation processes such as active site hydrolysis and alginate decarboxylation. Overall, this work contributes to the development of a sustainable and safe catalytic process for the efficient conversion of biobased glycidol and CO2 into a product with growing interest in the field of green chemistry as glycerol carbonate.